behave as no .venv if .venv is in project root and empty

pipenv/project.py

@@ -270,6 +270,10 @@ class Project:
         with io.open(dot_venv) as f:
             name = f.read().strip()
 
+        # If .venv file is empty, set location based on config.
+        if not name:
+            return str(get_workon_home().joinpath(self.virtualenv_name))
+
         # If content looks like a path, use it as a relative path.
         # Otherwise use directory named after content in WORKON_HOME.
         if looks_like_dir(name):

tests/integration/test_dot_venv.py

@@ -76,6 +76,36 @@ def test_venv_file(venv_name, PipenvInstance):
             assert venv_path == normalize_drive(venv_expected_path)
 
 
+@pytest.mark.dotvenv
+def test_empty_venv_file(PipenvInstance):
+    """Tests virtualenv creation when a empty .venv file exists at the project root
+    """
+    with PipenvInstance(chdir=True) as p:
+        file_path = os.path.join(p.path, '.venv')
+        with open(file_path, 'w') as f:
+            pass
+
+        with temp_environ(), TemporaryDirectory(
+            prefix='pipenv-', suffix='temp_workon_home'
+        ) as workon_home:
+            os.environ['WORKON_HOME'] = workon_home.name
+            if 'PIPENV_VENV_IN_PROJECT' in os.environ:
+                del os.environ['PIPENV_VENV_IN_PROJECT']
+
+            c = p.pipenv('install')
+            assert c.returncode == 0
+
+            c = p.pipenv('--venv')
+            assert c.returncode == 0
+            venv_loc = Path(c.stdout.strip()).absolute()
+            assert venv_loc.exists()
+            assert venv_loc.joinpath('.project').exists()
+            from pathlib import PurePosixPath
+            venv_path = normalize_drive(venv_loc.as_posix())
+            venv_path_parent = str(PurePosixPath(venv_path).parent)
+            assert venv_path_parent == Path(workon_home.name).absolute().as_posix()
+
+
 @pytest.mark.dotvenv
 def test_venv_file_with_path(PipenvInstance):
     """Tests virtualenv creation when a .venv file exists at the project root